na ##zar ##ov cy ##cl ##ization in particular is the generation of the pen ##tad ##ien ##yl cat ##ion followed by electro ##cy ##cl ##ic ring closure to an ox ##yal ##ly ##l cat ##ion . in order to achieve this transformation , the molecule must be in the s @ - @ trans / s @ - @ trans conform ##ation , placing the vinyl groups in an appropriate orientation . the prop ##ens ##ity of the system to enter this conform ##ation dramatically influences reaction rate , with α @ - @ substituted substrates having an increased population of the re ##quisite conform ##er due to ally ##lic strain . coordination of an electron dona ##ting α @ - @ sub ##sti ##tu ##ent by the
nazarov cyclization in particular is the generation of the pentadienyl cation followed by electrocyclic ring closure to an oxyallyl cation. in order to achieve this transformation, the molecule must be in the s @ - @ trans / s @ - @ trans conformation, placing the vinyl groups in an appropriate orientation. the propensity of the system to enter this conformation dramatically influences reaction rate, with α @ - @ substituted substrates having an increased population of the requisite conformer due to allylic strain. coordination of an electron donating α @ - @ substituent by the